1. Field of the Invention
This invention relates to a device for backwashing the bed of particulate material in an iron filter or a water conditioner.
2. Discussion of the Prior Art
As described in detail in Canadian Patent No. 1,273,721, which issued to the present inventor on Sep. 4, 1990, backwashing devices for use in iron filters and water conditioners tend to be somewhat inefficient. Examples of backwashing devices are found in U.S. Pat. Nos. 3,395,099, issued to R. D. Johnson on Jul. 30, 1968 and 3,455,458, issued to R. D. Johnson on Jul. 15, 1969. The Johnson devices employ separate, spaced apart tubes. In one embodiment of the Johnson inventions, particulate mineral is drawn into one of the tubes in a limited area beneath the tube. The other Johnson device involves separate, parallel tubes or a spiral tube on a second tube. In each case, suction for backwashing is created by means of a fine nozzle. It has been found that such devices become clogged to the point of inoperability. Moreover, such prior art devices cannot be used with commercial water treatment control valves with up flow brine controls, because the regenerative chemical will by-pass the bed.
The device as described in the above-identified Canadian patent goes a long way to providing an efficient backwash device. However, a problem encountered with the earlier invention is that of bed cementing, i.e. the bed of particulate material, particularly in the bottom of the tank, becomes compacted during use. The compaction or cementing is such that the portion of useful bed is substantially reduced, and the efficiency of the device suffers badly. Moreover, because of bed compaction during use of the water conditioner, when backwashing there is no movement of water through the bed at the lower end of the device, and consequently the water conditioner ultimately becomes completely inoperable. It is necessary to disconnect the water conditioner to restore water flow for normal household use. Cementing also promotes channelling in the particulate material, resulting in reduced efficiency prior to complete clogging. The use of somewhat complicated valves at the bottom end of applicant's earlier invention also led to problems such as the reverse flow of contaminants following a backwashing operation.